1. Field of the Invention
The invention described in this disclosure relates to and is particularly useful in preparing and storing reagents employed in enzyme immunoassays. In particular, the claimed invention is useful for stabilizing enzymes and enzyme conjugates which are used to detect and determine immunoreactants such as antigens, antibodies, binding proteins and haptens.
2. Description of the Prior Art
Chopra and Hollander both describe in U.S. Pat. Nos. 3,911,096 and 3,928,553, respectively, the usefulness of 8-anilino-1-napthalene sulfonic acid (ANS) as a "blocking agent" to inhibit the binding of triiodothyronine and/or thyroxine to thyroxine binding globulin. The reference patents point out that unextracted serum can be assayed for T.sub.3 and/or T.sub.4 without the interference of T.sub.4 binding globulin and thyroxine binding prealbumin by using a blocking agent such as ANS. The theory of utility, of course, is that the T.sub.3 and T.sub.4 binding sites on the binding globulin and prealbumin are occupied or blocked by ANS and the T.sub.3 and/or T.sub.4 are unbound and available for detection by an assay procedure.
U.S. Pat. No. 4,169,012 issued to Dawson, et al describes a method of stabilizing peroxidase compositions by adding polyvalent ions of groups 3 and 4 of the Periodic Table to reagents containing peroxidase compositions. The patentees of this method elaborate on their invention by alleging that reagents stabilized according to their method are particularly amenable to lyophilization.